Chair

ABSTRACT

A chair in which a backrest can be largely tilted rearward within a small rotation angle range without increasing the heights of a leg body and a seat body. The leg body ( 1 ) includes a pair of left and right side-legs ( 9 ) of angular shape in side view, each having a front leg ( 9   a ) tilting forward and downward and a rear leg ( 9   b ) tilting backward and downward. The lower end of a backrest support frame ( 3 ) is so pivotally mounted on the leg body ( 1 ) at an appropriate position under the seat body ( 2 ) as to be capable of tilting rearward between the left and right side-legs ( 9 ).

TECHNICAL FIELD

The present invention relates to a chair in which the backrest is pivotally mounted to a pair of legs, a seat being supported by a support base on the side legs.

BACKGROUND OF THE INVENTION

JP2002-282077A, JP2004-16516A, JP2004-33449A and JP2005-177180A disclose such a chair.

In the chair in JP2002-282077A and JP2004-16516A, the lower end of the backrest which can be tilted rearward is pivotally mounted to legs close to the rear end of the seat at approximately equal height. A radius of rotation from a pivot to the upper end of the backrest is limited.

This increases a rotation angle when the backrest is tilted rearward. In order to tilt the backrest greatly, it will be necessary to raise the leg and seat.

In JP2002-282077A, the lower end of the backrest is pivotally mounted to the legs at the rear end of the seat. When the backrest is tilted rearward, the chair becomes longer and requires a large space for the chair.

In JP2004-16516A, in order that the backrest may be tilted greatly, it is tilted after it is elevated by a linking mechanism. The structure is complicated and the number of parts and accessories increases.

In the documents, the right and left legs that support the seat are parallel with each other in a plan view and a front view. The seat is supported between the legs while it is close to or is in contact with the inner side surface of the legs, which makes the chair lack in lateral stability.

In JP2004-33449A and JP2005-177180A, the seat is supported by the support base at the upper end of the legs, and the lower end of the backrest is pivotally mounted. Even if the legs are lowered by elevating means to the lower limit, it will not be possible to go down the support base or seat supported by the support base. It will not be possible to provide a lower and large-tilted angle chair on which a person can sit in comfort posture.

The support base for supporting the seat is provided at the top of the legs. Even if four or five legs are mounted radially at the lower end, the chair will become unstable depending on one's posture.

In view of the disadvantages, it is an object of the present invention to provide a chair in which legs and a seat are in a low position and a large-tilted angle to make the chair more stable.

It is another object of the invention to provide a chair in which the backrest is tilted rearward greatly at a small angle of rotation, the chair reducing a rearward projecting distance and achieving comfortable sitting posture.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of a chair according to the present invention.

FIG. 2 is a front elevational view thereof.

FIG. 3 is a side elevational view thereof.

FIG. 4 is a side elevational view thereof when the backrest is tilted.

FIG. 5 is a rear elevational view thereof.

FIG. 6 is a perspective view of a leg unit.

FIG. 7 is a top plan view thereof.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

The chair 1 comprises a leg unit 1; a seat 2 supported by the leg unit 1; a backrest support frame 3 pivotally mounted at the lower front end to the leg unit 1; a backrest 6 comprising a mesh-like backrest plate 4 and a cushion 5; and a pair of rhombus-like armrests 7 at the lower part of the backrest support frame 3.

In FIGS. 6 and 7, the leg unit 2 comprises a pair of side legs 9,9 each comprising a front leg portion 9 a having a caster 8 at the front end and a rear leg portion 9 b having a caster 8 at the rear end, the rear leg portion being longer than the front leg portion 9 a; and a stretcher 10 between the side legs 9 and 9 at the upper ends.

The reason that the rear leg portion 9 b is longer than the front leg portion 9 a is to keep the chair more stable when the backrest 6 is tilted rearward.

The distance between the front leg portions 9 a and 9 a of the side legs 9 gradually becomes greater forward, and the distance between the rear leg portions 9 b and 9 b gradually becomes greater rearward thereby making the leg unit 1 more stable.

A shorter shaft 11 is integrally formed with the upper end of each of the side legs 9. A mounting piece 12 projects downward from the inner side surface of the front end of the rear leg portion 9 b in FIG. 3.

The upper ends of a pair of vertical portions 10 a,10 a of the stretcher 10 are engaged with the shorter shafts 11 with a bolt 13. A lateral rod 10 b disposed behind the vertical portion 10 a is engaged with the mounting piece 12 with a bolt 13.

A head of the bolt 13 disposed in the shorter shaft 11 is covered with a circular cap 14 (not shown in FIG. 5) mounted in a groove of the side of the shorter shaft 11.

A support base 15 for supporting the seat 2 is fixed at the rear end to a projection 10 c in the middle of the lateral rod 10 b of the stretcher 10 with a bolt 16 so that the front end of the support base 15 projects ahead of the lateral rod 10 b.

The vertical portion 10 a of the U-shaped stretcher 10 is fixed at the upper end to the top of the side leg 9, and the lateral rod 10 b is fixed to the mounting piece 12 of the rear leg portion 9 b, such that the upper end of the support base 15 is slightly higher than the top of the side leg 9.

In FIGS. 3 and 5, the backrest support frame 3 stands at the rear end of the seat; and comprises a pair of side frames 17,17 each having an arm 17 a at the lower end which slants diagonally backward and an arc-like top frame 18 connecting the upper ends of the side frames 17,17 to each other.

The distance between the right and left side frames 17 and 17 is shorter than that that between the right and left rear leg portions 9 b and 9 b of the pair of side legs 9. When the backrest support frame 3 is tilted rearward, the arms 17 a,17 a do not engage with the rear leg portions 9 b and 9 b.

In FIG. 6, at the front end of each of the arms 17 a, there is formed a rounded portion 17 b nearly coaxial with the shorter shaft 11 at the top of the side leg 9. The rounded portion 17 b is pivotally coupled to a torsion shaft (not shown) such as a known rubber torsion unit of a reclining mechanism in the support base 15 while it is forced counterclockwise anytime. Thus, the backrest support frame 3 and backrest 6 mounted thereto are tilted rearward around the support base 15 when the backrest 6 is pushed rearward by a sitting person.

In FIGS. 3 and 6, a pair of seat-support links 20,20 is pivotally mounted to a cylindrical support 19 projecting transversely from the support base 15, with a pivot shaft 21.

Seat-support pieces 22,22 project upward from the front end of the arm 17 a of the backrest support frame 3. A rectangular armrest mounting portion 23 projects with the seat-support piece 22 on the upper surface of the arm 17 a.

A seat frame 24 mounted on the lower surface of the seat 2 is pivotally mounted at the front end to the upper end of the seat support link 20, and is pivotally mounted at the rear end to the upper end of the seat-support piece 22 with a pivot shaft 26 as shown in FIG. 3.

Thus, the front part of the seat 2 is supported by the support base 15 coupled with the leg unit 1 with the seat support link 20, and the middle part of the seat 2 by the arms 17 a of the backrest support frame 3 with the seat support piece 22.

Accordingly, in FIG. 4, when the backrest support frame 3 is tilted rearward with the backrest 6, the seat 2 is tilted rearward together. After the seat 2 is assembled, the rear part of the front leg portion 9 a and the front part of the rear leg portion 9 b are positioned inside the side edges of the seat 2, so that the side legs 9 of the leg unit 1 do not project sideward as shown in FIG. 2.

As described above, in the embodiment of a chair according to the present invention, the backrest support frame 3 is pivotally mounted at the front lower end to the support base 15 coupled to the leg unit 1 increasing a rotation radius from the pivot to the upper ends of the backrest support frame 3 and backrest 6. Thus, the backrest 6 can be tilted more extensively at a small rotation angle, and a rearward projection can be minimized.

The chair can be inclined rearward extensively without increasing heights of the leg unit 1 and seat 2 thereby providing a low and backward-tilting chair with sitting comfort.

In the embodiment, the front ends of the backrest support frame 3 and seat 2 are pivotally mounted to the support base 15 on the lateral rod 10 b of the stretcher 10. The support base 15 is as high as the top of the side leg 9 reducing one's sitting height and improving sitting comfort.

The arm 17 a of the backrest support frame 3 is relatively long and tilted upward and rearward below the seat 2. The arm 17 a is pivotally mounted at a position which is almost as high as the top of the side leg 9 increasing a rotation angle of the arm 17 a and avoiding the rear end of the arm 17 a from getting in touch with the floor.

The distances between the front leg portions 9 a and 9 a and between the rear leg portions 9 b and 9 b become greater forward and rearward respectively, and the rear leg portions 9 b are longer than the front leg portions 9 a thereby keeping the chair more stable when the backrest 6 is tilted rearward.

Since the distance between the front leg portions 9 a and 9 a becomes greater forward, a lower limb of the sitting person is unlikely to hit the front leg portion 9 a.

In the foregoing embodiment, the arm 17 a of the backrest support frame 3 is pivotally mounted to the support base 15, but may be pivotally mounted to the tops of side legs or inner side surfaces of the short shafts.

In the foregoing embodiment, the seat 2 is tilted together with the backrest support frame 3, but the seat 2 may be fixed to the top of a leg unit including a support base. 

1-12. (canceled)
 13. A chair comprising: a seat; a backrest standing at a rear end of the seat; a pair of backrest support frame supporting the backrest on a front surface; and a leg unit supporting the seat and comprising a pair of side legs, each of the side legs comprising a front leg portion and a rear leg portion, a distance between the front leg portions gradually becoming greater forward, a distance between the rear leg portions gradually becoming greater rearward, each of the rear leg portions being longer than each of the front leg portions, each of the pair of backrest support frames being pivotally mounted to each of the pair of side legs under the seat so that the backrest support frame can be tilted rearward between the side legs.
 14. The chair of claim 13, further comprising a pair of shorter shafts, each of which is positioned at a top of each of the side legs between the front leg portion and the rear leg portion, the backrest support frame being tilted around the shorter shafts.
 15. The chair of claim 14 wherein a pair of arms that is provided at lower ends of the pair of backrest support frames is pivotally mounted to the pair of side legs at almost equal height to the top of the side legs.
 16. A chair comprising: a seat; a leg unit supporting the seat and comprising a pair of side legs, each of the side legs comprising a front leg portion and a rear leg portion, a distance between the front leg portions gradually becoming greater forward, a distance between the rear leg portions gradually becoming greater rearward, each of the rear leg portions being longer than each of the front leg portion; a support base provided on the leg unit and supporting the seat; and a stretcher provided between tops of the side legs, the support base being provided in the middle of the stretcher.
 17. The chair of claim 16 wherein the stretcher comprises a lateral rod and a vertical portion at each end, the support base being provided on an upper surface of the lateral rod, upper ends of the vertical portions being fixed to a top of the pair of side legs.
 18. The chair of claim 17 wherein the vertical portion extends upward and forward to allow the lateral rod to be positioned behind the top of the side legs.
 19. The chair of claim 16 wherein the front ends of a pair of arms of the backrest support frame is pivotally mounted to each end of the support base so that the backrest support frame can be tilted rearward.
 20. The chair of claim 18 wherein a front part of the support base projects ahead of a top of the side legs, front side ends of the seat being pivotally mounted to side ends of side legs with a lateral pivot shaft, side ends of a rear part of the seat being pivotally mounted to the arms of the backrest support frame with a lateral pivot shaft. 